Please get an appointment with an psychiatrist and start looking out for an therapist before the ruminations (that’s what that is called) turn darker. A partner will not help with this more than in the short term, I speak from long years of experience.

There are multiple probable causes for ruminations: depression, trauma and personality disorders are the most common ones. only a psychiatrist can get you an correct diagnosis, which will help pinpoint where the ruminations come from, but the way out is always therapy.

But you can be sure that you are not bad or gross or something like that - your mind is just fixated on bad thoughts and experiences. Others will have a completely different picture of you. Knowing how my mind works when caught in my “loop”, you don’t believe one word of that, but it still needed to be said :-)